Rolling mills

ABSTRACT

A four-high rolling mill is provided with backup roll bending on the lower backup roll only. The compensating bending moment is applied to the roll by means of controllable pressure applying means operably engaged with neck portions of the roll outboard of the bearing chocks and with a stiff beam extending beneath the housings and projecting outwardly therefrom. A four-high mill can be designed and erected without provision for backup roll bending and by later positioning the stiff beam beneath the housings, backup roll bending can be applied to the lower backup roll.

United States Patent [72] Inventor Harry Laurence Fred Bondl-lathersage, near Sheffield. England [211 App]. No. 766,851 [22 Filed0a.". 1968 [45] Patented Aug. 3, 1971 [73] Assignee Davy and UnitedEngineering Company Limited Sheffield, England [32] Priority Oct. 13,1967 [33] Great Britain [31 I 46868/67 [54] ROLLING MILLS 2 Claims, 1Drawing Fig.

[52] [1.5. CI 72/237, 72/245 [51] Int. Cl 821i 37/00 [50] Field ofSearch 72/237,

[ References Cited UNITED STATES PATENTS 3,171,305 3/1965 Stone 72/2453,250,105 5/1966 Stone 72/245 2,897,538 8/1959 Shapiro et 31.. 72/2453,355,925 12/1967 Barnikel et 31 72/244 Primary Examiner-Milton S. MehrAltorney-l-lenry C. Westin ABSTRACT: A four-high rolling mill isprovided with backup roll bending on the lower backup roll only. Thecompensating bending moment is applied to the roll by means ofcontrollable pressure applying means operably engaged with neck portionsof the roll outboard of the bearing checks and with a stiff beamextending beneath the housings and projecting outwardly therefrom. Afour-high mill can be designed and erected without provision for backuproll bending and by later positioning the stiff beam beneath thehousings, backup roll bending can be applied to the lower backup roll.

PATENTED ms 3|97l 3596.488

INVENTOR HARRY LLFI Banb 4 ATTORNEY ROLLXNG MILLS This invention relatesto rolling mills having a pair of work rolls and a pair of backup rolls,such mills being known as four-high mills.

The work I'OilS of a four-high rolling mill are positioned between thepair of backup rolls which reinforce the smaller diameter work rolls andresist the tendency of the work rolls to bend when metal to be rolledenters the gap between them and produces a load, known as the rollingload, on the work rolls. When the rolling load is very large even therelatively massive backup rolls tend to bend to some extent and thiscauses the rolled metal product, usually in the form of sheet or stripto be of nonuniform shape, that is the product varies in the thicknessacross its width with the edges thinner than the center.

it is known to provided controllable pressure applying means operablyengaged with the mill housings and neck portions of both backup rollsoutboard of their supporting bearing chocks for impairing on both of therolls a bending moment which compensates for bending of the backup rollsand the work rolls due to forces imposed thereon during a rollingoperation. The controllable pressure applying means take the form ofhydraulic piston and cylinder assemblies and due to the very high forceswhich are involved, the assemblies and due to the very high forces whichare involved, the assemblies are of considerable size and addconsiderably to the cost of the mill. Furthermore it is necessary toprovide extra stiff mill housings which are capable of withstanding theforces imposed thereon during backup roll bending and again this adds tothe cost of the mill.

Many rolling mill operators are not prepared to pay the considerableextra cost of a four-high rolling mill having provision for backup rollbending on both backup rolls and would prefer to purchase a mill withoutprovision for backup roll bending but to which backup roll-bendingequipment could be applied at a later date if the need for suchequipment arises. With the known backup roll bending arrangement wherethe pressureapplying means act between the mill housings and the necksof the backup rolls, this is not possible unless the mill housings areinitially supplied oversize. That is, the mill housings are designed towithstand the backup bending forces which will eventually be imposed onthem. This means that the initial cost of the housings is greater thanfor an equivalent mill which is not designed to have backup rollbending. If the mill operator eventually decides not to purchase theextra backup roll-bending equipment to modify his mill then the extrainitial cost of the mill housings is wasted. A mill operator seeking topurchase a mill which can subsequently be converted for backup rollbending on both backup rolls also has a further problem regarding thebackup rolls which he purchases. If he purchases conventional backuprolls without extended necks then these rolls are useless and have to bereplaced with rolls having extended necks when the mill is converted forbackup roll bending.

It is an object of the present invention to provided a rolling mill inwhich at least some of the above-mentioned difficulties are overcome.

According to a first aspect of the present invention a rolling mill hasa pair of housings, upper and lower work rolls'and upper and lowerbackup rolls supported in bearing chocks mounted in windows defined bysaid housing said lower backup roll having a neck portion at each endthereofextending outwardly of the bearing chocks of the roll andcontrollable pressure applying means operably engaged with said neckportions outboard of the bearing chocks and with a stiff beam extendingbeneath the housings and projecting outwardly therefrom for imposing onsaid roll a bending moment to compensate for bending of at least thatroll due to the forces imposed thereon during a rolling operation.

Since the roll-bending forces are taken in the main by the stiff beamwhich extends beneath the mill housings then the housings themselves donot have roll-bending forces exerted upon them and accordingly can be ofsmaller dimensions than would be the case if the bending forces acteddirectly on the housing. This means that a four-high rolling 'mill notdesigned for the use of backup roll bending can be adapted tosubsequently receive roll bending on the lower backup roll.

in accordance with a second aspect of the present inven tion, for arolling mill having a pair of housings, upper and lower work rolls andupper and lower backup rolls supported in bearing chocks mounted inwindows defined by said housings, an attachment comprises a stiff beamadapted to extend beneath the housings with end portions of the beamprojecting outwardly of the housings and a pair of hydraulic piston andcylinder assemblies mounted one on each of said end portions of thebeam, and operably engageable with neck portions at each end of thelower backup roll outboard of the bearing chocks of that roll forimposing on said roll a bending moment to compensate for bending of atleast that roll due to the forces imposed thereon during a rollingoperation.

It is not an operation of great difficulty to position the stiff beambeneath the housings of an existing rolling mill. The housings aremounted on a concrete foundation and part of the foundation can bebroken away to enable the beam to be slid into position without the millbeing moved. If the possibility of adding backup roll bending on thelower backup roll is envisaged when the mill is installed, a channellarge enough to receive the beam can be made in the foundation when thefoundation is laid. Furthermore, the stiff beam could be positioned inthe foundation before the mill is positioned on it thereby avoiding thenecessity of breaking away part of the foundation at a later date. Inany event, as shown in the drawing, the beam contacts the housingsinward of its opposite ends. lf the beam is never used, its initial costis wasted but this is considerably less than making the mill housingoversize.

If the backup roll bending is subsequently applied to the lower backuproll of a mill then a new lower backup roll provided with extended neckportions is required, but the original roll is not wasted as this can beused as a spare for the upper backup roll.

By providing compensatory bending on the lower backup roll only, theshape of the product rolled by the mill is not necessarily uniform butit is more uniform than when no compensatory roll bending is provided.For many uses of strip or sheet produced by mill having compensatoryroll bending on one roll, the shape is acceptable whereas the shape ofsheet or strip from the same mill when no compensatory roll bending isprovided would not be acceptable.

In order that the invention may be more readily understood, it will nowbe described, by way of example only, with reference to the accompanyingdrawing which is an elevation, partly in section of a rolling mill inaccordance with one embodiment of the invention.

A rolling mill has two massive spaced apart housings land 2. Eachhousing defines a window 3. A pair of large diameter backup rolls 4 and5 are supported at each end in bearing chocks slidably mounted in thewindows 3. The chocks of the upper backup roll 4 are indicated byreference numeral 6. A pair of work rolls 7 and 8, of smaller diameterthan the backup rolls are disposed between the backup rolls and resupported at their ends in bearing chocks (not shown) positioned in thewindows. A mill top 9 extends between the housings and supportsconventional screw down equipment which includes screws lll which actagainst the chocks 6. By rotating the screws the vertical position ofthe upper backup roll relative to the housings can be adjusted.

The lower backup roll 5 is provided with roll-bending equipment to applya bending moment to the roll to compensate for bending of at least thatroll due to the forces imposed thereon during a rolling operation. Theroll-bending equipment comprises a still beam 12 which may be offabricated construction and of box section and which extends beneath thehousings land 2 and projects outwardly from each housing. The housingsare secured to a concrete foundation not shown and the beam 12 may bepositioned in the foundation. A pair of hydraulic piston and cylinderassemblies 13 and 14 have their cylinders rigidly secured to therespective end portions of the beam which project outwardly from thehousings. The piston in each cylinder is connected through a piston rod15 to a bearing housing 16 mounted on an extended neck portion 17 of thelower backup roll. The bearing housings 16 are outboard of the bearingchocks in the housing.

In use, without the piston and cylinder assemblies being actuated, thebackup rolls bend as shown in an exaggerated form by the broken lineswhen metal 18 to be rolled passes through the gap between the work rollsand applies a rolling load to the rolls. By supplying hydraulic fluidunder pressure to the cylinders of the assemblies 13 and 14, the pistonrods 15 apply a bending moment to the lower backup roll which causes theroll to bend in the opposite direction to that cause by the rollingload. By adjusting the ending forces applied to the roll by the pistonand cylinder devices, the bending of the roll due to the rolling loadcan be compensated for. The bending forces act between the roll necksand the beam 12 and the bending forces do not act upon the screws 1 l.

The screws 11 experience the rolling load and when, as in the knownarrangement, the upper backup roll is provided with compensatory rollbending then the roll-bending forces for the upper backup roll also acton the screws. This means that the screws experience both the rollingand the bending forces and this can cause wear to take place in thescrewoperating means if an attempt is made to rotate the screws duringoperation of the mill. By applying roll bending only to the lower backuproll this serious difficulty is considerably lessened. Furthermorehydraulically operable extensible means in the form of a pair ofhydraulic piston and cylinder assemblies 19 can be interposed onebetween the lower end of each screw 11 and the chocks of the upperbackup roll. The screws 11 can then be used to provide coarse adjustmentof the roll gap when the mill is not rolling and the assemblies 19 canbe energized to provide fine adjustment of the roll gap when the mill isin use.

In accordance with the provisions of the patent statues, l

have explained the principle and operation of my invention and haveillustrated and described what I consider to represent the bestembodiment thereof.

1 claim: 7

l. A rolling mill having a pair of spaced apart housings each defining awindow, upper and lower work rolls supported in bearing chocks mountedin said windows, upper and lower backup rolls supported in bearingchocks mounted in said windows, said lower backup roll having neckportions at each end extending outwardly of the bearing chocks, afurther bearing each of said neck portions, a stiff beam positionedbeneath said housings parallel to the longitudinal axes of the rolls andprojecting outwardly beyond said housing and having portions contactingsaid housings inward of said further bearings and a pair of verticalmembers extending normal to the longitudinal axes of the rolls andengaging the further bearings and rigidly connected to parts of thestiff beam which project outwardly beyond the housings, said memberseach including an hydraulically operable piston and cylinder device foradjusting the axial length of the member between the further bearing andthe stiff beam.

2. For a rolling mill having a pair of housings, upper and lower workrolls and upper and lower backup rolls supported in bearing chocksmounted in windows defined by the housings, the lower backup roll havingneck portions at each end extending outwardly of the bearing chocks anda further bearing on each of said neck portions an attachment comprisinga stiff beam arranged to be positioned beneath the housings parallel tothe longitudinal axis of the rolls and projecting outwardly beyond thehousings and having portions contacting said housings inward of saidfurther bearings, and a pair of vertical members extending normal to thelongitudinal axes ofthe rolls and engaging the further bearings andrigidly connected to parts of the stiff beam which project outwardlybeyond the housings, said members each including an hydraulicallyoperable piston and cylinder device for ad usting the axis length of themembers between the further bearing and the stiff beam.

1. A rolling mill having a pair of spaced apart housings each defining awindow, upper and lower work rolls supported in beAring chocks mountedin said windows, upper and lower backup rolls supported in bearingchocks mounted in said windows, said lower backup roll having neckportions at each end extending outwardly of the bearing chocks, afurther bearing each of said neck portions, a stiff beam positionedbeneath said housings parallel to the longitudinal axes of the rolls andprojecting outwardly beyond said housing and having portions contactingsaid housings inward of said further bearings and a pair of verticalmembers extending normal to the longitudinal axes of the rolls andengaging the further bearings and rigidly connected to parts of thestiff beam which project outwardly beyond the housings, said memberseach including an hydraulically operable piston and cylinder device foradjusting the axial length of the member between the further bearing andthe stiff beam.
 2. For a rolling mill having a pair of housings, upperand lower work rolls and upper and lower backup rolls supported inbearing chocks mounted in windows defined by the housings, the lowerbackup roll having neck portions at each end extending outwardly of thebearing chocks and a further bearing on each of said neck portions anattachment comprising a stiff beam arranged to be positioned beneath thehousings parallel to the longitudinal axis of the rolls and projectingoutwardly beyond the housings and having portions contacting saidhousings inward of said further bearings, and a pair of vertical membersextending normal to the longitudinal axes of the rolls and engaging thefurther bearings and rigidly connected to parts of the stiff beam whichproject outwardly beyond the housings, said members each including anhydraulically operable piston and cylinder device for adjusting the axislength of the members between the further bearing and the stiff beam.